Attaching Yagi To Tracker

I do not understand at the moment, how it's possible to attach yagi antenna to tracker.
Do you have any ideas about it?

My only thought that Yagi can be attached to one of the "ears" of tracker, and attach counterweight to other ear.
Is it wahat you mean?Yuriy7th Mar 201619:14

Good question Yuriy.

As you can see in this image: http://imgur.com/OaMc6DP , there is a two part antenna clamp that fits over the end of the Elevation pipe. The first is pressed onto the EL pipe and is secured with a screw as can be seen in detail beginning on step 5.1.36 of the assembly procedure.

Then the antenna is squeezed and held into place by a cap that is installed over the antenna using screws.

This arrangement allows the antenna to be moved forward and aft to balance the load on the arm and ease the strain on the gear train and motor. It also allows for an easy way to replace the antenna for various reasons.

A counter weight on the other side can be created by attaching weights to the Elevation pipe, or even by hanging a small cup filled with some sand or other weight from the Elevation pipe.

I hope that clears it up for you.

Wade

Wade7th Mar 201620:19

Thanks, Wade.
Now I understand meaning of "Antenna Clamp" stl.

I can see, however, that antenna is attached "vertically".
TV antennas of the same design (at least it looks similar) are normally "horizontal".
Does it matter if it is horizontally or vertically attached?
Yuriy11th Mar 201612:16

Hi Yurly

I hope that I am not speaking out of turn, but, the position of the antenna should be horizontal position when calibrating. Just as the antenna should be positioned North when calibrating.

So, if the antenna is pointed vertical, then the controller has rotated it 90 degrees vertically.

Unless, you need to set the antenna vertically as 'home' position, which will require some software changes, but will work fine.

Bobbie14th Mar 201606:28

Thank you Bobbie, but it's not exactly what I have asked about.
Please look here: https://commons.wikimedia.org/wiki/File:Yagi_TV_antenna_1954.png
It's a normal TV YAGI antenna. As you may see, the elements are arranged in horizontal plane.

Compare this with Wade's picture: http://imgur.com/OaMc6DP
On this picture, the elements of antenna are arranged in vertical plane.

As far as I understand now, the difference is polarisation. Wrong polarisation means, as far as I understand, much lower gain. And it's near to impossible to predict the polarisation of spacecraft's signal. From other point of view, YAGI antennas was used a lot to receive a satellites signals with much of success.
Yuriy14th Mar 201608:06

Hello Yuriy,

The image that I sent up last was really only to show the clamp that you asked about. The photo was taken with the tracker on my work bench on a support pole I use for testing. I don't leave the antenna attached normally of course, nor do I leave a normal EL pipe attached, as I don't want to take up so much area of my bench as I swing it around during testing.

The fact of the matter is that the EL arm could be considerably longer and be able to support an antenna in almost any orientation or position that the user desires to put it at.

An example is here: http://imgur.com/nTRkVVr

I hope this clears up the question for you.

Thanks

Wade
Wade14th Mar 201618:46

Sorry that I mis-understood your question Yuriy.

While listening to some of the ham radio sats, I rotate the yagi to 45 degrees to vertical, as some of the satellites are vertically polarized and some horizontally polarized (a compromise), and most are circularly polarized in which case a complex dual feed yagi is used with half the elements horizontal and half are vertical (actually two yagi antennas).

If the satellite antenna rotates, then a circularly polarized is needed or the signal will be degraded..

I would like for someone from the ThumbSat group to clarify which type of antenna is needed..

I had presumed that the satellite antenna will not rotate since a standard yagi antenna is the only type listed.
Bobbie22nd Mar 201622:09

Hi Wade

the antenna system you posted to http://imgur.com/nTRkVVr seems to be a dual band circular polarized system. Did you build them or are they commercial antennas?

They look better designed than my ham radio 245Mhz/445Mhz antennas...Bobbie22nd Mar 201622:15

Hi Bobbie.

Unfortunately, I don't have any details on where it came from.

That particular image is from our ThumbNet volunteer in Prague, Czech Republic.

Martin is pretty sharp, so it wouldn't surprise me if he built them himself to that level of quality, but I just don't know.